1. Field of the Invention
The current invention relates to rechargeable battery systems, and more particularly, to systems and methods for controlling the charging of rechargeable batteries.
2. Description of the Related Art
Batteries are typically used in situations where steady electric current is needed but not readily available from a power line. Portable electronic devices, for example, are typically powered by batteries. Rechargeable batteries allow for the repeated use of the same batteries by recharging them. Although many rechargeable batteries are recharged in dedicated chargers, a growing number of electronic devices contain an integrated charger allowing for the recharging of the device's batteries while the batteries remain inside the device. Examples include mobile and handheld computers and portable music players. Advantages of recharging the batteries inside the electronic device in which they are used include that there is no need to remove and re-insert the batteries, which reduces the risks of losing the batteries or inserting them incorrectly, and there is no need for a separate battery charger, which reduces the number of items that need to be manufactured, packaged, and tracked together with the portable electronic device itself. Additionally, recharging the batteries inside the electronic device increases portability and mobility by reducing the components associated with the product that a user may need to carry when traveling or on the go.
Rechargeable batteries allow for bidirectional conversion between electrical and chemical energy, as opposed to non-rechargeable batteries which allow for only the conversion of chemical energy into electrical energy, but not vice versa. Chargers provide electrical current to rechargeable batteries, which convert the received electrical energy back into storable chemical energy. Rechargeable batteries typically have limited lifetimes. The lifetime and utility of a rechargeable battery depend on factors such as the battery type (e.g., battery chemistry, construction, and size), the way it is drained, and the way it is recharged. Providing too much current and continuing to charge after the battery is fully charged are actions likely to reduce the overall health of the battery.
The simplest chargers provide a relatively steady current to the battery. More advanced chargers provide more elaborate charging characteristics that can vary with one or more factors, such as time, battery voltage, battery type, battery current, battery impedance, and battery temperature. Such advanced functionality is typically provided by an integrated circuit (IC) controller.